One type of adhesive container for supplying molten hot melt thermoplastic adhesive to dispensing devices comprises a cylindrical-shaped hopper or container in which a heated feed ram is axially movable to force the hot melt adhesive through a discharge outlet in the container to one or more dispensing devices. The feed ram is moved axially downwardly within the adhesive container until a predetermined quantity of adhesive is discharged therefrom, at which time the ram is withdrawn to expose the open top of the container and permit loading of more adhesive for heating and subsequent discharge from the container.
In the course of discharge of adhesive from the container, or while the ram is removed from the container to permit loading of additional adhesive, fumes in the form of gaseous emissions are released from the heated adhesive and flow upwardly toward the open top of the container. It is important to collect these gaseous emissions before they escape to atmosphere.
Fume collection devices have been utilized in the past to collect fumes emitted from adhesive supply containers, but these devices are of limited effectiveness. Typically, fume collection devices are connected to a source of vacuum which draws ambient air surrounding the container toward inlet openings in the collection device so that the gaseous emissions from the interior of the container are entrained within such air flow and drawn through the inlet openings into the collection device. One problem with collection devices of this type is that turbulence is usually created in such air flow, particularly as the air enters the inlet openings of the collection device, which reduces the effectiveness of the emission recovery operation. Additionally, an unacceptable amount of gaseous emissions can escape upwardly from the open top of the container in the immediate area of the collection device before they become entrained in the flow of air entering the collection device.
The same problems identified above in connection with adhesive supply containers are also present in containers for the supply of other material such as coating compositions. In the coating and finishing industry, for example, a major concern is the environmental effect of the escape of solvent components of paint. Using collection devices of the type described above, it has been found that the solvents present in paint are often ineffectively captured as they evaporate and escape as gaseous emissions from the paint formulation, resulting in contamination of the surrounding atmosphere. Additionally, since most solvents react with oxidants, pollution problems of toxicity, odor and smog may be created as a result of the ineffective recovery of gaseous solvents escaping from the coating formulation.